The invention relates to the field of blood pumps.
Here and in the following, a blood pump is understood as a pump which serves the assistance or establishing of a flow of blood within a human or animal body and is suitable for implanting in the chest area of a human or animal outside the heart. With left ventricular blood pumps (left ventricular assist devices, LVADs), there is a connection between the left half of the heart and an inlet of the blood pump as well as between an outlet of the blood pump and the aorta branching from the heart to assist or establish the blood circulation through the body (systemic circulation). With right ventricular blood pumps (RVADs), there is a connection between the right half of the heart and the pulmonary trunk which leads to the left and right pulmonary arteries (or a direct connection between the RVAD and the left and/or right pulmonary artery/arteries) to assist or establish the blood circulation through the lung (pulmonary circulation). The blood is conducted within the blood pump through a hollow body which is part of a pump housing or is arranged in such a pump housing. A rotating impeller having blading for generating a pressure and a flow of the blood resulting therefrom is provided in the hollow body. So-called total artificial heart (TAH) pumps include left and right ventricular blood pumps to assist or establish the total blood circulation. Connections hoses and tubes as well as optionally flow manifolds are used to establish the named connections between the blood pump and the heart or the blood vessels. In addition, at least one cable harness is required for the energy supply and optionally for the control of the blood pump, said cable harness connecting the blood pump to an energy reservoir and optionally to a control unit. Alternatively, the pump can be transcutaneously supplied with energy.
One main problem in the implanting and use of such blood pumps is the space requirement of such blood pumps and of the connection hoses as well as the cable harness in the chest space close to the heart.
A further difficulty can be found in the risk of destruction of blood cells (hemolysis) by the blood pump, in particular at mechanical bearings of the impeller, in constrictions or abrupt changes in direction of the flow of blood through the blood pump and by high pressure gradients within the blood pump. In the design of blood pumps, mechanical bearings of the impeller are for this purpose frequently replaced with a magnetic and/or hydrodynamic bearing apparatus.
Numerous blood pumps are known in the prior art. A blood pump is disclosed in WO 2007/105842 A1 which includes an impeller having a rotor, wherein the impeller is placed onto a first conducting body in the manner of a sleeve. A rotor is understood here and in the following in each case as a motor rotor, i.e. a component of the motor which is stored in a cavity of the impeller in some embodiments and which is formed by a magnet. The pump moreover includes a guide wheel. With the help of magnetic bearings, the impeller is radially supported on the guide body and axially supported between the guide bodies.
A centrifugally operating pump is proposed in each of U.S. Pat. No. 6,015,272, U.S. Pat. No. 6,244,834, U.S. Pat. No. 6,447,265 and U.S. Pat. No. 6,447,266 which has a pump housing having a central spigot or pin. An impeller having a bore corresponding to the spigot moves on this spigot, with the outer shape of the impeller or its hub being conical. The blading of the impeller is attached to this conical outer surface and effects the primarily centrifugally operating pumping power. A blood gap in which a secondary flow path arises is formed between the inner cylindrical surface of the rotor and the spigot. Permanent magnets are used to support the impeller in the radial direction and actively regulated magnets to support the impeller in the axial direction. The fluid is expelled from the pump through a spiral outlet.
U.S. Pat. No. 5,370,509 shows a blood pump, wherein the guide body tapers conically in the upstream direction and an impeller having a blading varying in the radial extent is formed on the conical guide body. A stator which is disposed within the guide body and which acts on a rotor arranged in the impeller is located in the proximity of the wall of the tangential chamber disposed downstream for driving the impeller. Due to the conical form, further magnets are used for the axial and radial support which are also arranged in the pump housing.
A further pump is shown in U.S. Pat. No. 5,211,546. It is in this respect an axially operating pump in which the impeller is placed onto a pin-like guide body in the manner of a sleeve. Furthermore, guide wheels which are connected via guide vanes to a wall of the tube surrounding the impeller are located upstream and downstream of the impeller. The guide wheels have magnetic bearings for the improved axial support of the impeller.
Although the initially named heart pumps are occasionally already in practical use, there is still the need for high-performance, space-saving pumps.
It is the object of the present invention to propose a blood pump which takes up the aforesaid problem and offers an improvement.